Why do we have the divison of Hanafi's and malikis and others if the holy book is one?

If the holy book is one and it has mentioned of how to pray, why do we have the variations of prayer between the Islamic scholars Hanafi,Maliki,Shafi'i,Hanbali,Zahiri Why is there a difference of so much between the beliefs and prayers,fasting of the above islamic scholars ? What is the universal way of praying the regular Salat, Jummuah, Eid ,Bakrid prayers ?